Overview
- University of Tokyo astronomer Tomonori Totani reports a halo-shaped gamma-ray excess around the Milky Way after analyzing 15 years of NASA Fermi data, with results published in JCAP.
- The spectrum rises and falls sharply around 20 GeV and matches predictions for annihilating WIMPs with particle masses about 500 times that of a proton, including a compatible annihilation rate.
- The analysis excluded the bright galactic plane and the inner roughly 10 degrees, modeled known backgrounds, and identified a residual not readily explained by common astrophysical sources.
- Independent researchers caution that Fermi backgrounds and modeling choices can mimic such signals, citing alternatives like pulsars, emissions related to the Fermi bubbles, or analysis artifacts.
- Next tests highlighted by both supporters and skeptics include searching for the same 20 GeV signature in dwarf galaxies, deeper scrutiny with CTAO and further Fermi data, and cross-checks from underground direct-detection experiments.